A large body of research links testosterone and cortisol to male-male competition. Yet, little work has explored acute steroid hormone responses to coalitional, physical competition during middle childhood. Here, we investigate testosterone, dehydroepiandrosterone, androstenedione, and cortisol release among ethnically Chinese boys in Hong Kong, aged 8–11 years, during a soccer match and an intrasquad soccer scrimmage, with 63 participants competing in both treatments. The soccer match and intrasquad soccer scrimmage represented out-group and in-group treatments, respectively. Results revealed that testosterone showed (...) no measurable change. DHEA increased during both treatments in the majority of participants and the degree of change had no relation to independent variables or covariate measures. Most boys experienced androstenedione increases during match play, but no significant differences during the intrasquad soccer scrimmage competitions. The magnitude of change differed significantly between treatments and was positively associated with age. These latter findings suggest boys’ androstenedione responses may be sensitive to competitor type. For most subjects, cortisol significantly increased during match play, decreased during the intrasquad soccer scrimmage, and differed significantly between treatments, suggesting each treatment promoted a different psychological state among competitors. Cortisol/DHEA molar ratio decreased during the intrasquad scrimmage, suggestive of a more relaxed mental state. These data shed new light on potential proximate mechanisms associated with coalitional competition among prepubescent boys, with relevance to adrenarche and life history theory. (shrink)

Attention has been given to cross-cultural differences in adolescent growth, but far less is known about developmental variability during juvenility (ages 3–10). Previous research among the Pumé, a group of South American foragers, found that girls achieve a greater proportion of their adult stature during juvenility compared with normative growth expectations. To explain rapid juvenile growth, in this paper we consider girls’ activity levels and energy expended in subsistence effort. Results show that Pumé girls spend far less time in subsistence (...) tasks in proportion to their body size compared with adults, and they have lower physical activity levels compared with many juveniles cross-culturally. Low activity levels help to explain where the extra energy comes from to support rapid growth in a challenging environment. We suggest that activity levels are important to account for the variation of resource and labor transfers in mediating energy availability. (shrink)